This invention relates to a corner connecting clip and more particularly to an invertible corner connecting clip with a tactile indicator for use in assembling main cross members to form a ceiling latticework.
Clean room facilities require a dust-free environment which may be accomplished by covering the ceiling with a plurality of filters to allow a flow of clean filtered air into the clean room. A ceiling latticework is required to support the filters and a sealing system must be provided at the periphery of the filters where they are supported by the latticework to avoid bypass air leakage around the filters.
In such clean room facilities it is the practice to assemble a ceiling latticework of speed main and cross support members which define rectangular filter receiving openings. These support members are in the form of a channel formed by bottom and spaced side walls capable of containing a liquid sealant such as petroleum jelly. The filters fit into the rectangular openings and have depending peripheral flanges which seat in the sealant to seal the filter. The particulate laden air enters a chamber above the ceiling and passes downward through the filters into the clean room working area. The avoidance of bypass air leakage around the filters and into the clean room is very important. If the latticework is in a class 10 clean room, a cubic foot of air therein can contain no more than 10 particles one-half micron or larger. A cubic foot of outdoor air may contain two and one-half billion particles. The connections between the main and cross support members offer a prime source for bypass air leakage and the design and assembly of these corner areas is very important to avoid such bypass air leakage or leakage of the liquid sealant.
In assembling the latticework, the bottom and side walls of each cross member must be carefully joined and connected in fluid tight relation with the bottom and side walls of the main support members. At the present time, clean room ceilings as large as 40,000 to 50,000 square feet in area are being constructed. The standard filter element used is only 2 feet by 4 feet in size and, therefore, assembly of the filter supporting latticework requires that thousands of corner connections be made. The latticework must be assembled overhead with the installers working on scaffolds and from ladders where assembly and visual inspection are difficult. The assembly of a liquid tight latticework is very labor intensive resulting in inordinately high installation costs for clean room ceilings. Heretofore no satisfactory solution has been found to the problem of providing a ceiling latticework assembly which can be constructed error-free overhead to provide strong, reliable, low cost fluid tight connections between the main and cross members in a simple manner requiring a minimum of assembly time so that labor costs will be minimized.